Mechanistic pathway of water adsorption to impact on the nonlinear elasticity of single-crystalline ZnO NWs

Surface modification via adsorbates is significant for property prediction in nanostructures where surface effect is dominant. This is especially vital for zinc oxide (ZnO) nanowires (NWs) which has no native passivation layer. As water is an ubiquitous environmental factor and its aggregation on ZnO surface is favoured, molecular statics (MS) simulations are used to study the deformation of ZnO with surface water adsorption in the finite strain regime (up to 0.1). Three types of water covered surface structures are considered to examine their effects on the size-dependence of linear () and nonlinear () elastic moduli. The pathway of adsorption to impact NWs is identified by revealing the radial distribution of , and residual stress for the NWs. The physical origins of the water adsorption effects are further discussed in terms of the layer-wise equilibrium structure and potential energy variation